Bella missing in Horfield

Hi, my black cat Bella has been missing for over 4 days. She does go off occasionally but is usually back within 24hrs. She’s a beautiful looking cat with piercing yellow eyes. She’s very slender and small for her age. She used to be a stray, so I’m hoping that helps her survive. Because of this she can be very spikey! She doesn’t like to be touched, so approach with caution! She does wonder the field behind my house (Downend Rd, Horfield) but also goes Rd side too. If anyone has seen her please can you let me know, I’m starting to worry. She’s around 12 years old approx but does not look it!